Air Force & NASA Fire Off Green Rocket 157
coondoggie writes "NASA and the Air Force said today they had successfully launched a 9-ft. rocket 1,300 feet into the sky, powered by aluminum powder and water ice. This combination of fuel elements, referred to as ALICE, has the potential to replace some liquid or solid propellants. The technology is being developed at Purdue University and Pennsylvania State University. Aside from its environmental benefiits, ALICE has the advantage that it could be manufactured in far-away places, such as the moon or Mars, instead of being transported to distant horizons at great cost, researchers said."
Re:Aluminum powder is green? (Score:5, Informative)
It is easier to produce and easier to store: no need for high-pressure supercooled storage as needed for H2 and O2 storage. Besides, pure O2 is a very dangerous material to handle, which is why in most labs O2 cylinders are at relative low pressure. A leak can cause a fire: grease can combust spontaneously when in contact with pure O2. So handling H2 and O2 costs a lot of effort and energy. That makes them expensive as well. And in general: higher total cost means more resources used and that is always bad for the environment.
Hydrazine is also a very bad poison. Maybe not when it is burnt completely - but 100% combustion is always hard to reach, and I'm too lazy to look up the combustion of hydrazine now. And again it is a real danger in the handling stage. Or when a rocket were to explode upon launch, that is also still a real issue.
Many other solid propellants are either poisonous themselves, or have bad combustion products. Commonly used propellants are very expensive too.
This nAl-H2O (nAl = nano-Aluminium) product is very interesting as the combustion products are Al2O3 (silica) and H2. In the solid state it is also safe, you can probably eat it without adverse health effects. No nutritional values though, the Al particles likely pass unchanged.
And it has other interesting applications as well: nAl-H2O can be stored safely and easily long term, not much risk of leaks as it is a toothpaste-like substance at room temperature. If you were to bring pure nAl particles on e.g. a submarine you can use the reaction with sea water to propel your submarine with the heat of the reaction directly or with the H2 that is produced.
And finally nAl is relatively cheap to produce and Al is plentiful on this planet, water of course also doesn't cost much, and as such it can be a really cheap alternative to current fuels. Production of Al from ore takes a lot of electricity as it is an electrolysis process, which is an environmental issue, though this can be solved by using water, wind or even solar power.
Re:Aluminum powder is green? (Score:3, Informative)
Free Aluminum is non-inert (that's kind of the entire point of a rocket which uses free aluminum as one of its fuels). Aluminum bound to oxygen (like that which is found in water ice, aluminum's bond is more powerful that hydrogen), on the other hand, can be (depending on formula of course) one of the strongest bonds in the natural world. Bauxite (AL2O3) is very inert compared to most other compounds.
Just because one of the chemicals involved is non-inert doesn't mean the product will be non-inert. Chemistry 101 and the existence of Salt teaches that.
Re:Aluminum powder is green? (Score:3, Informative)
Side note re hydrazine; 100% combustion is not only impossible it is undesirable for rockets. Most are run a little fuel rich so that there are unburned and partially burned molecules in the exhaust which are lighter than the oxides you would get from complete combustion, and thus for the same energy give slightly higher exhaust velocity.
Hydrazine pollution is a big part of why the Russians are planning to dump Proton for Angara; on the face of it a foolish decision because Proton is cheap, reliable, and almost as capable as the basic Angara designs in terms of payload and orbit. The rationale is that a significant of the cost of a Proton launch is cleaning up the chemical residues it spurts across Kazahkstan.
Re:Ethical question (Score:3, Informative)
it. Every other element they spell correctly.
Next, lets pick on the yanks for avoiding metric measurements
Re:Hm... (Score:3, Informative)
You build one "standard rocket" on Earth, which is capable of going to the moon.
You fill it with fuel, and send it off to the moon. It arrives with empty tanks.
Now, at this point, you have one "standard rocket" sans fuel, sitting on the moon. The rocket had to have had around 15 km/sec deltaV when it started, which was just about enough to go to the moon and land there.
You refuel it from fuel made on the moon. Now you have a rocket with 15 km/sec deltaV sitting on the moon.
Hmm, how far can you go with that...tough one. Allow for 5 km/sec to be blown on the landing wherever we're going to land. It probably won't be that much, since we'll probably use aerobraking to some extent, but let's be generous. 10 km/sec left.
We launch from the moon, on an orbit that'll pass within 500 km of the Earth's surface, where we'll make a second burn to send us outbound....
The rocket leaves the vicinity of Earth at somewhat more than solar escape speed.
In other words, such a "standard rocket", if refueled on the moon from fuel made on the moon, and relaunched, can go basically anywhere in the Solar System. It can do it relatively quickly (relative to what we can currently launch - we're not talking hundreds of km/sec here). Jupiter in a year, Mars in a few weeks, that sort of thing....
Re:Aluminum powder is green? (Score:2, Informative)
I have an O2 cylinder in my garage that runs 3000psi when full. Welding gas, y'know. Every mechanic's shop has one. Hydrogen is also used as a welding gas, it is commonly stored and shipped in the same truck as the O2 cylinders. Along with propane, acetalene, MAP gas, etc.
Aluminum is -very- expensive to produce compared to liquefied gas. Its refined from bauxite by electrolysis. They put the Al refineries next to hydroelectric dams instead of next to the bauxite mine, that should tell you something eh?
Not saying it couldn't work nicely as a propellant for use on the moon or asteroids, where water ice and recoverable aluminum could be found. Thermite could too. Just saying calling it green is tripe.
Although I have to say, the thought of refining pure aluminum on the moon is PURE science fiction. Electrolysis of molten rock, hard to do in a space suit with a refiner unit hauled up from Earth, right? Electrolysis of the ice for use as a hydrogen/oxygen rocket would be easier, yes? Solar panel, couple plastic bags and a compressor pump.